Self-organized storage nodes for distributed delivery network

ABSTRACT

A distributed delivery network for capacity enhancement of a communication link shared by multiple communication devices for network access service. The distributed delivery network may include one or more distributed storage devices, some of which may include at least one rotating disk storage device, a network interface, and one or more environmental sensors. Each distributed storage device may monitor data from the environmental sensor(s) and transition between an active state where messages are stored in or retrieved from the storage device, and a standby state where access is suppressed. The distributed storage devices may self-organize control operations for the distributed delivery network including message storage and retrieval and redundancy of messages, which may be determined by frequency of requests for the messages.

CROSS REFERENCES

The present application for patent claims priority to U.S. ProvisionalPatent Application No. 62/153,823 by Dankberg, et al., entitled,“SELF-ORGANIZED STORAGE NODES FOR DISTRIBUTED DELIVERY NETWORK”, filedApr. 28, 2015, assigned to the assignee hereof and expresslyincorporated by reference herein.

BACKGROUND

Field of the Disclosure

The present disclosure relates to broadband communications in general,and in particular, to a distributed delivery network for providingcapacity enhancement in broadband communications networks.

Relevant Background

As the use of communications and networking continues to grow around theworld, users are demanding a high-quality broadband experience even inremote areas or mobile environments. The ability to provide ahigh-quality broadband experience in these environments presents manychallenges.

SUMMARY

Methods, systems, and devices are described for providing capacityenhancement in broadband communication networks. In some examples, theeffective capacity of a communication link between a network andmultiple communication devices is enhanced by using a distributeddelivery network to store messages for subsequent delivery to thecommunication devices. The communication devices may receive networkaccess service via a network gateway device that communicates over theshared communication link. The distributed delivery network may includeone or more distributed storage devices, which may be connected with thenetwork gateway device via a local network.

In some examples, each distributed storage device includes at least onerotating disk storage device, a network interface for communicating withthe network gateway device, and one or more environmental sensors. Eachdistributed storage device may include a control circuit to manageoperation of the distributed storage device. The control circuit maymonitor data from the environmental sensor(s) and transition thedistributed storage device between an active state where messages arestored in or retrieved from the rotating disk storage device, and astandby state where access of the rotating disk storage device issuppressed to protect the rotating disk storage device.

The distributed delivery network may provide control of message flow andmessage redundancy for messages requested by the communication devicesvia the network gateway device. For example, redundancy of messages onthe distributed delivery network may be determined by frequency ofrequest of the messages. The distributed storage devices mayself-organize control operations for the distributed delivery network.In some examples, one distributed storage device may operate as a leaderdevice for message flow in the distributed delivery network. The leaderdevice may monitor the operational states of distributed storage devicesand maintain an index of messages stored in the distributed storagedevices for retrieval. The leader device may also monitor message flowvia the network gateway device and manage redundancy for messages storedin the distributed delivery network. The leader device may be staticallydefined or may be dynamically selected based on a predetermined orpseudo-random selection scheme.

A communications system including a network gateway device and aplurality of distributed storage devices coupled to the network gatewaydevice is described. In some aspects, a distributed storage device ofthe plurality of distributed storage devices includes a housing, arotating disk storage device within the housing, a network interface tosupport communication with the network gateway device, a sensor toproduce a sensor signal indicating a characteristic of an environmentexternal to the housing, and a control circuit to detect an adverseoperating condition for the rotating disk storage device based on thesensor signal, and to transition the distributed storage device from anactive state to a standby state upon detection of the adverse operatingcondition. When in the active state, the distributed storage device mayenable access of the rotating disk storage device to store messagesreceived via the network interface, to retrieve the stored messages inresponse to requests received via the network interface, and to providea given stored message of the stored messages for redundancy of storagewithin other distributed storage devices of the plurality of distributedstorage devices based on a frequency of requests for the given storedmessage. When in the standby state, the distributed storage device mayprevent access to the rotating disk storage device.

In some examples, upon transitioning from the active state to thestandby state, the distributed storage device transmits an indicationthat the distributed storage device is unavailable. The indication thatthe distributed storage device is unavailable may be, for example,broadcast over a storage area network coupled with the network gatewaydevice and the plurality of distributed storage devices. In someexamples, the transition of the distributed storage device from theactive state to the standby state is performed independently of anoperational state of at least one other distributed storage device ofthe plurality of distributed storage devices.

According to some aspects, when in the standby state the distributedstorage device configures the rotating disk storage device in aprotected state. The protected state may include, for example, one ormore of a parked media state, a deactivated state, or an unpoweredstate.

According to some aspects, when in the standby state the control circuitmay detect a safe operating condition for the rotating disk storagedevice based on the sensor signal and transition the distributed storagedevice from the standby state to the active state upon detection of thesafe operating condition.

In some examples of the communication system, the control circuit maydetermine that the distributed storage device is operating as a leaderdevice for the plurality of distributed storage devices. The controlcircuit may, for example, determine that the distributed storage deviceis operating as the leader device for the plurality of distributedstorage devices based on a result of a consensus election.

In some examples, the control circuit may, while the distributed storagedevice is operating as the leader device, determine a change for anindex of the stored messages across the plurality of distributed storagedevices, and broadcast the change for the index to the plurality ofdistributed storage devices.

In some examples, the control circuit may determine that the distributedstorage device is no longer operating as the leader device for theplurality of distributed storage devices. The control circuit maymonitor broadcast messages for indications of changes to the index anupdate the index upon based on received indications of changes to theindex.

In some examples, the control circuit may, while the distributed storagedevice is operating as the leader device, monitor for periodic statusmessages from the plurality of distributed storage devices, determinethat a second distributed storage device from the plurality ofdistributed storage devices is unavailable based upon not receiving aperiodic status message from the second distributed storage device, andflag one or more messages stored in the second distributed storagedevice as unavailable in the index.

In some examples, the control circuit may, while the distributed storagedevice is operating as the leader device, receive a request for a firstmessage, determine that the first message is stored in a firstdistributed storage device of the plurality of distributed storagedevices, retrieve the first message from the first distributed storagedevice, and provide the first message in response to the request.

In some examples, the control circuit may, while the distributed storagedevice is operating as the leader device, receive a request for a firstmessage, determine that the first message is stored in a firstdistributed storage device of the plurality of distributed storagedevices, and provide a proxy address of the first message at the firstdistributed storage device in response to the request.

In some examples, the control circuit may, while the distributed storagedevice is operating as the leader device, determine an amount ofredundancy for storing a the given stored message in the plurality ofdistributed storage devices based on the frequency of requests, andforward the given stored message for storing in one or more distributedstorage devices of the plurality of distributed storage devices based onthe determined amount of redundancy.

According to some aspects, the plurality of distributed storage devicesincludes a first set of distributed storage devices having a firstreliability characteristic and a second set of distributed storagedevices having a second, lower reliability characteristic. In someexamples, the control circuit may, while the distributed storage deviceis operating as the leader device, determine that the frequency ofrequests for the given stored message exceeds a threshold, and forwardthe given stored message for storing in a distributed storage device ofthe first set of distributed storage devices.

In some examples, the control circuit may receive information related toan impending adverse operating condition for the rotating disk storagedevice and transition the distributed storage device from the activestate to the standby state based on the impending adverse operatingcondition.

In some examples, the control circuit may detect a failure of therotating disk storage device and broadcast an indication that thedistributed storage device is unavailable based on the detected failure.

According to some aspects, the control circuit may perform a periodicdiagnostic scan on the rotating disk storage device. In some examples,the control circuit may determine one or more storage locations of therotating disk storage device failing the periodic diagnostic scan,identify one or more messages stored in the one or more storagelocations, broadcast an indication that the one or more messages areunavailable, and flag the one or more storage locations as unavailablefor further use.

According to some aspects, the network interface comprises any of awired networking interface, a wireless networking interface, orcombinations thereof.

According to some aspects, the distributed storage device includes afitting mounted to the housing for coupling with an external bracket,and a release lever coupled with the fitting to release the fitting fromthe external bracket.

According to some aspects, the network gateway device provides networkaccess service for a mobile environment via a shared wirelesscommunication link. The mobile environment may be, for example, anaircraft, and the plurality of distributed storage devices may belocated on the aircraft. The shared wireless communication link may be asatellite communications link.

According to some aspects the sensor may include any of an inertialmeasurement sensor, a gyroscope, a temperature sensor, or combinationsthereof.

A method for enhancing capacity of a communication system is described.The method may include providing a distributed storage device of aplurality of distributed storage devices coupled to a network gatewaydevice in the communications system. The method may include operatingthe distributed storage device in an active state, the operatingincluding providing access of a rotating disk storage device to storemessages received via a network interface, retrieving the storedmessages in response to requests received via the network interface, andproviding a given stored message of the stored messages for redundancyof storage within other distributed storage devices of the plurality ofdistributed storage devices based on a frequency of requests for thegiven stored message. The method may include detecting an adverseoperating condition for the rotating disk storage device of thedistributed storage device based on a sensor signal from a sensor of thedistributed storage device indicating a characteristic of an environmentof the distributed storage device, transitioning the distributed storagedevice from the active state to a standby state upon detection of theadverse operating condition, and preventing, in the standby state,access to the rotating disk storage device.

According to some aspects, the method includes transmitting, upontransitioning from the active state to the standby state, an indicationthat the distributed storage device is unavailable. The method mayinclude configuring, in the standby state, the rotating disk storagedevice in a protected state.

According to some aspects, the method includes detecting, in the standbystate, a safe operating condition for the rotating disk storage devicebased on the sensor signal, transitioning the distributed storage devicefrom the standby state to the active state upon detection of the safeoperating condition.

According to some aspects, the method includes determining that thedistributed storage device is operating as a leader device for theplurality of distributed storage devices. The determining that thedistributed storage device is operating as the leader device for theplurality of distributed storage devices may be based on a result of aconsensus election.

According to some aspects, the method includes, when the distributedstorage device is operating as a leader device for the plurality ofdistributed storage devices, determining a change for an index of thestored messages across the plurality of distributed storage devices, andbroadcasting the change for the index to the plurality of distributedstorage devices.

According to some aspects, the method includes determining that thedistributed storage device is no longer operating as the leader devicefor the plurality of distributed storage devices, monitoring broadcastmessages for indications of changes to the index, and updating the indexupon based on received indications of changes to the index.

According to some aspects, the method includes, when the distributedstorage device is operating as a leader device for the plurality ofdistributed storage devices, monitoring for periodic status messagesfrom the plurality of distributed storage devices, determining that asecond distributed storage device from the plurality of distributedstorage devices is unavailable based upon not receiving a periodicstatus message from the second distributed storage device, and flaggingone or more messages stored in the second distributed storage device asunavailable in the index.

According to some aspects, the method includes, when the distributedstorage device is operating as a leader device for the plurality ofdistributed storage devices, receiving a request for a first message,determining that the first message is stored in a first distributedstorage device, retrieving the first message from the first distributedstorage device, and provide the first message in response to therequest.

According to some aspects, the method includes, when the distributedstorage device is operating as a leader device for the plurality ofdistributed storage devices, receiving a request for a first message,determining that the first message is stored in a first distributedstorage device, and providing an address of the first message at thefirst distributed storage device in response to the request.

According to some aspects, the method includes, when the distributedstorage device is operating as a leader device for the plurality ofdistributed storage devices, determining an amount of redundancy forstoring the given stored message in the plurality of distributed storagedevices based on the frequency of requests, and forwarding the givenstored message for storing in one or more distributed storage devices ofthe plurality of distributed storage devices based on the determinedamount of redundancy.

According to some aspects, the method includes receiving informationrelated to an impending adverse operating condition for the rotatingdisk storage device and transitioning the distributed storage devicefrom the active state to the standby state based on the impendingadverse operating condition.

According to some aspects, the method includes detecting a failure ofthe rotating disk storage device, and broadcasting an indication thatthe distributed storage device is unavailable based on the detectedfailure.

According to some aspects, the method includes performing a periodicdiagnostic scan on the rotating disk storage device. In some examples,the method includes determining one or more storage locations of therotating disk storage device failing the periodic diagnostic scan,identifying one or more messages stored in the one or more storagelocations, broadcasting an indication that the one or more messages areunavailable, and flagging the one or more storage locations asunavailable for further use.

Further scope of the applicability of the described systems, methods,apparatuses, or computer-readable media will become apparent from thefollowing detailed description, claims, and drawings. The detaileddescription and specific examples are given by way of illustration only,since various changes and modifications within the scope of thedescription will become apparent to those skilled in the art.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of embodiments ofthe present disclosure may be realized by reference to the followingdrawings. In the appended figures, similar components or features mayhave the same reference label. Further, various components of the sametype may be distinguished by following the reference label by a dash anda second label that distinguishes among the similar components. If onlythe first reference label is used in the specification, the descriptionis applicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 shows an example communications environment for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

FIG. 2 shows an example communications environment for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

FIG. 3 shows an example communications environment for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

FIG. 4. shows a diagram of an example distributed storage device for adistributed delivery network in accordance with various aspects of thedisclosure.

FIG. 5 shows an example operational state diagram for a distributedstorage device 140 in accordance with various aspects of the disclosure.

FIG. 6 shows a flow diagram of an example message flow for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

FIG. 7 shows a flow diagram of an example message flow for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

FIG. 8 shows a diagram of an example operational state table inaccordance with various aspects of the disclosure.

FIG. 9 shows an example dynamic leader selection state diagram for adistributed delivery network in accordance with various aspects of thedisclosure.

FIG. 10 shows a block diagram of a control circuit for a distributedstorage device in accordance with various aspects of the disclosure.

FIG. 11 shows a block diagram of a control circuit for a distributedstorage device in accordance with various aspects of the disclosure.

FIG. 12 shows a simplified diagram of an example satellitecommunications system which may implement capacity enhancement using adistributed delivery network in accordance with various aspects of thedisclosure.

FIG. 13 shows a diagram illustrating example locations for installationof distributed storage devices on an aircraft in accordance with variousaspects of the disclosure.

FIG. 14 shows a diagram illustrating alternative example locations forinstallation of distributed storage devices on an aircraft in accordancewith various aspects of the disclosure.

FIG. 15 shows a flowchart diagram of an example method for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

FIG. 16 shows a flowchart diagram of an example method for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

DETAILED DESCRIPTION

The described feature generally relate to capacity enhancement of ashared communication link using a distributed delivery network. Thedistributed delivery network may include multiple distributed storagedevices, which may each include a rotating disk storage device. Thedistributed delivery network may self-organize for managing message flowand redundancy while distributed storage devices may enter and leave thedistributed delivery network at any time.

This description provides examples, and is not intended to limit thescope, applicability or configuration of embodiments of the principlesdescribed herein. Rather, the ensuing description will provide thoseskilled in the art with an enabling description for implementingembodiments of the principles described herein. Various changes may bemade in the function and arrangement of elements.

Thus, various embodiments may omit, substitute, or add variousprocedures or components as appropriate. For instance, it should beappreciated that the methods may be performed in an order different thanthat described, and that various steps may be added, omitted orcombined. Also, aspects and elements described with respect to certainembodiments may be combined in various other embodiments. It should alsobe appreciated that the following systems, methods, devices, andsoftware may individually or collectively be components of a largersystem, wherein other procedures may take precedence over or otherwisemodify their application.

The rise in consumption of network multimedia content such as systemsproviding audio and video on demand (AVOD) and use of audio and videosharing services (e.g., YouTube, Vine, etc.) has dramatically increasedconsumer bandwidth usage. In addition, users increasingly expect ahigh-quality broadband experience while travelling. For example, thereis a growing demand for network access service during air travel, andthe desire to be able to access network multimedia content on airplanesand in other mobile environments has created challenges in providingsufficient bandwidth for users over bandwidth-limited wireless networks.

In various mobile environments, multiple users may be provided networkaccess service via a shared communication link. For example, users mayconnect their communication devices to a wireless local area network(WLAN), which routes data communications to other networks (e.g., theInternet) via the shared communication link. The shared communicationlink may be a wireless link (e.g., cellular link, satellitecommunications link, etc.), and may have limited communicationbandwidth. For example, while the resources (e.g., frequency, time,etc.) of a wireless network may be flexibly applied for multiple users,the overall capacity of the network may be limited, and congestion canoccur when users request more resources at a particular time than thenetwork can support. Increasing bandwidth for wireless communicationssystems is expensive and sometimes additional usable spectrum isunavailable. Therefore, providing a high-quality network accessexperience at a reasonable cost in mobile environments presents manychallenges.

FIG. 1 shows an example communications environment 100 for capacityenhancement of network access service in accordance with various aspectsof the disclosure. The communications environment 100 includes a networkgateway device 150-a that provides network access service to multiplecommunication devices 115 in a mobile environment 105 via a sharedcommunication link 110-a. The communication devices 115 may be mobiledevices (e.g., smartphones, laptops, tablets, netbooks, and the like)and may communicate with the network gateway device 150-a viacommunication links 125. Communication links 125 may be, for example,part of a local network such as a WLAN supported by an access point165-a.

The shared communication link 110-a may be a wireless communication linkbetween the network gateway device 150-a located on the mobileenvironment 105 and one or more networks 120, which may include anysuitable public or private networks and may be connected to othercommunications networks such as the Internet, telephony networks (e.g.,Public Switched Telephone Network (PSTN), etc.), and the like. Theinformation rate for servicing the communication devices 115 may dependon the number of communication devices 115 in the mobile environment 105and types of traffic requested by the users, and may vary over time. Forexample, the network traffic provided over the shared communication link110-a may include a mix of web traffic, streaming traffic, and othertypes of traffic. The types of network traffic that generally consumethe most communication resources are file sharing and videocommunications (e.g., video conferencing, video streaming, etc.) withsome estimates indicating that as much as 50% of all Internet traffic isvideo streaming traffic.

The probability distribution of requested content tends to benon-uniform. For example, the same streaming traffic may be requested bymultiple users at different points in time, or may be shared acrossmultiple users if they request broadcast or multicast traffic. In onespecific example, the percentage of unique messages of one popular videolibrary requested as a function of message requests is approximatelylog-linear, with 20% of the unique messages accounting for approximately85% of the message requests. Similarly, content such as “viral” videosmay be repeatedly requested by many different users within a span ofdays or even hours.

The capacity of shared communication link 110-a may be flexible to meetthe information rate demands of the communication devices 115. However,the information rate provided by shared communication link 110-a mayhave limits given by system bandwidth, hardware limitations (e.g., powerconstraints), or overall system capacity. For example, communicationsenvironment 100 may be part of a communications system, which may have alimited overall information rate capacity. In addition, the incrementalcost for the information rate provided over shared communication link110-a may be relatively high. While it may be possible to restrict sometypes of traffic (e.g., high definition video, etc.), this may degradethe network access experience for various users. These and other issuesof providing network access service in mobile environments typicallyresult in high cost of service, a reduced quality user experience, orboth.

One way to increase the effective information rate of the sharedcommunication link 110-a is to store some content locally to the mobileenvironment 105. For example, when a communication device 115 makesrequests for a set of messages from network 120 via the sharedcommunication link 110-a, the messages can also be stored in a storagesystem connected to network gateway device 150-a. If the same set ofmessages are then later requested by other communication devices 115,the stored messages can be provided from the local storage instead ofbeing re-sent over the shared communication link 110-a. The amount ofeffective information rate enhancement provided by locally storedcontent depends on the amount of storage, the reliability of the storagesystem, and the probability distribution of requested messages. Toprovide a significant effective increase in information rate (e.g., 2×or higher) provided to the communication devices 115, the local storagecapacity required may be large. For example, to cover a substantialpercentage of streaming traffic (e.g., 10-50%), storage capacities inthe 10-200 Terabyte (TB) range may be necessary.

Different types of storage media may have different trade-offs betweenstorage capacity and reliability. For example, a rotating disk storagedevice (commonly known as a hard disk drive (HDD)) uses a rotatingmagnetic media platter with a read and write head that operates over themagnetic surface to detect and modify magnetization of the magneticmedium on the platter. Rotating disk storage devices have relativelyhigh storage capacity while providing data access in any desired order(e.g., random access). A solid state drive (SSD) is a data storagedevice that uses non-volatile solid state (e.g., NAND flash memory,magnetoresistive random-access memory (MRAM), etc.) to persistentlystore data (maintain data when powered off). Compared with HDDs, SSDsare typically more resistant to physical shock, run silently, have loweraccess time, and less latency. In addition, SSDs may be more reliablethan HDDs in some environments. For example, because HDDs haveread/write heads that float above spinning platters, HDDs may besusceptible to shock and vibration, as well as other mechanical failuremechanisms. Because SSDs have no moving parts, mechanical failure ratesfor SSDs are generally low. However, SSDs may have a limited number ofwrite cycles (or erase cycles), which may affect life-time of the drivein certain applications.

Higher cost is a substantial drawback to the use of SSDs for largercapacity storage applications. For example, consumer-grade SSDs may beapproximately 10 times more expensive per unit of storage thanconsumer-grade HDDs. Although prices for SSDs are declining, theconsumer price for SSDs may currently be in the range of $500-$1500 perTB of storage (depending on drive storage size) compared toapproximately $40-80 per TB for HDDs. Additionally, the availablestorage capacity in a single HDD device is generally larger than thatavailable for a single SSD device. For example, the largest available3.5″ consumer HDDs may be in the 8-12 TB range, while the largestavailable SSDs, although a smaller form factor, may be in the 1-2 TBrange. Thus, many more SSD devices may be necessary to provide a giventotal storage size.

To create a storage system using multiple drive devices, datavirtualization techniques such as redundant array of independent disks(RAID) may be used to combine multiple drive devices into a singlelogical unit that stores data using redundancy techniques. A commonlyused RAID technique is data mirroring where a set of data is written totwo or more drive devices, and the data is available as long as at leastone drive device is functional. Another RAID technique for use with morethan two drive devices is striping with distributed parity information.Striping with distributed parity information may provide highereffective storage capacity for a given total storage size but is onlytolerant of failure of a single drive device. Fault tolerance may beincreased by increasing the parity information (e.g., double parityinformation for fault tolerance of up to two failed drives, etc.), atthe expense of effective capacity.

In some cases, the mobile environment 105 may be subject to substantialshock and vibration, as well as other extreme environmental conditions.For example, the mobile environment 105 may be an aircraft, which maysuffer from vibration due to engines and hydraulic systems, and mayencounter turbulence that results in significant gravitational forces(g-forces) seen by components on the aircraft. Other mobile environmentssuch as ships and trains may also see significant shock or vibrationoccur intermittently. Providing a robust and cost-effective localstorage solution for increasing effective information rate for a sharedcommunication link in these types of mobile environments thus presentsmany challenges.

In embodiments, the communications environment 100 is configured toincrease the effective capacity between the network 120 and the mobiledevices 115 by using a distributed delivery network 130-a to storemessages for subsequent delivery to communication devices 115. Thedistributed delivery network 130-a includes one or more distributedstorage devices 140-a, which may be connected with the network gatewaydevice 150-a via a local network link 155-a (e.g., storage area network(SAN), etc.). Each distributed storage device 140-a may include at leastone rotating disk storage device (e.g., HDD, etc.), a network interface(e.g., Ethernet, WLAN, etc.) for communicating with the network gatewaydevice 150-a, one or more environmental sensors such as an inertialmeasurement sensor (e.g., accelerometer, etc.), a gyroscope, atemperature sensor, and the like. Each distributed storage device 140-amay include a control circuit to manage operation of the distributedstorage device 140-a within the distributed delivery network 130-a. Thecontrol circuit may monitor data from the environmental sensor(s) andtransition the distributed storage device 140-a between an active statewhere messages are stored in or retrieved from the rotating disk storagedevice, and a standby state where access of the rotating disk storagedevice is suppressed to protect the rotating disk storage device.Operational state transitions may be performed independently andautonomously by each distributed storage device 140-a according to thelocal environmental conditions experienced by the distributed storagedevice 140-a, which may be different than environmental conditionsexperienced by other distributed storage devices 140-a.

The distributed delivery network 130-a may provide control of messageflow and message redundancy for messages requested by the communicationdevices 115 via the network gateway device 150-a. For example,redundancy of messages on distributed delivery network 130-a may bedetermined according to a storage policy that is based on frequency ofrequest of the messages. The distributed storage devices 140-a mayself-organize control operations for distributed delivery network 130-a.In some examples, one distributed storage device 140-a may operate as aleader device for message flow in the distributed delivery network130-a. The leader device may monitor the operational states ofdistributed storage devices 140-a and maintain an index of messagesstored in the distributed storage devices 140-a for retrieval. Theleader device may also monitor message flow via the network gatewaydevice 150-a and manage redundancy for messages stored in thedistributed delivery network 130-a. The leader device may be staticallydefined or may be dynamically selected based on a predetermined orpseudo-random selection scheme.

FIG. 2 shows an example communications environment 200 for capacityenhancement of network access service in accordance with various aspectsof the disclosure. The communications environment 200 includes a networkgateway device 150-b that provides network access service to multiplecommunication devices (not shown) within mobile environment 105 via ashared communication link 110-b. The shared communication link 110-b maybe a wireless communication link between the network gateway device150-b located on the mobile environment 105-b and networks 120 (e.g.,private networks, the Internet, etc.). Communications over the sharedcommunication link 110-b may be performed by a modem 220, which may beintegrated with the network gateway device 150-b, or may be a separatecomponent, in some examples.

In communications environment 200, network gateway device 150-b isconnected to multiple wireless access points (WAPs) 165-b (e.g., WAP165-b-1, 165-b-2, 165-b-m, etc.), which provide connection points forthe communication devices to connect to network gateway device 150-b andrequest content via shared communication link 110-b. WAPs 165-b may bedistributed about the mobile environment 105-b, and may provide trafficswitching or routing functionality (e.g., as part of a WLAN extendedservice set (ESS), etc.).

As illustrated in FIG. 2, communications environment 200 includesdistributed delivery network 130-b to increase the effective capacity ofshared communication link 110-b. Distributed delivery network 130-bincludes multiple distributed storage devices 140-b (e.g., 140-b-1,140-b-2, 140-b-n, etc.), which each may include the components ofdistributed storage devices 140-a discussed with reference to FIG. 1.Each distributed storage device 140-b may operate as a separate logicalstorage node on distributed delivery network 130-b. The distributedstorage devices 140-b may be distributed in different locationsthroughout the mobile environment 105-b, and may communicate withnetwork gateway device 150-b via one or more WAPs 165-b. The distributedstorage devices 140-b may also communicate directly with each other(e.g., peer-to-peer) for selecting a leader device and managing messageflow in distributed delivery network 130-b.

FIG. 3 shows an example communications environment 300 for capacityenhancement of network access service in accordance with various aspectsof the disclosure. The communications environment 300 includes a networkgateway device 150-c that provides network access service to multiplecommunication devices (not shown) within mobile environment 105-c via ashared communication link 110-c. The shared communication link 110-c maybe a wireless communication link between the network gateway device150-c located on the mobile environment 105-c and networks 120 (e.g.,private networks, the Internet, etc.). Communications over the sharedcommunication link 110-c may be performed by a modem 220-a, which may beintegrated with the network gateway device 150-c, or may be a separatecomponent, in some examples. In communications environment 300, networkgateway device 150-c is connected to multiple wireless access points(WAPs) 165-c (e.g., WAP 165-c-1, 165-c-2, 165-c-m, etc.), which may bethe WAPs 165-b discussed above with reference to FIG. 2.

As illustrated in FIG. 3, communications environment 300 includesdistributed delivery network 130-c to increase the effective capacity ofshared communication link 110-c. Distributed delivery network 130-cincludes multiple distributed storage devices 140-c (e.g., 140-c-1,140-c-2, 140-c-n, etc.), which each may include the components ofdistributed storage devices 140 discussed with reference to FIG. 1 or 2.Each distributed storage device 140-c may operate as a separate logicalstorage node on distributed delivery network 130-c. The distributedstorage devices 140-c may be distributed in different locationsthroughout the mobile environment 105-c, and may communicate withnetwork gateway device 150-b via network 155-c, which may be a wirednetwork. In some examples, network 155-c may be a storage area network(SAN) (e.g., Ethernet, Fibre Channel, etc.). The distributed storagedevices 140-c may also communicate directly with each other (e.g.,peer-to-peer) via network 155-c for selecting a leader device andmanaging message flow in distributed delivery network 130-c.

In some examples of communications environments 100, 200 or 300,messages may be pre-loaded or pushed to a distributed delivery network130 from one or more content providers. For example, a content providermay be allocated a portion of a distributed delivery network 130 forpre-loading with highly-requested content. Distributed delivery network130 may determine redundancy for the messages in the pre-loaded content.For example, distributed delivery network 130 may store messages thatare more frequently requested (e.g., based on historical information ofthe content provider, etc.) with higher redundancy. In some examples,the pre-loaded or pushed content may be updated based on changes infrequency of requests for the content. For example, the distributeddelivery network 130 may determine that certain content of the pushedcontent is seldom requested in the mobile environment 105, and may adaptthe portion of the content of the content provider that is pre-loadedbased on the requests for content in the mobile environment 105. In someexamples, updating of the pre-loaded or pushed content may be performedduring times of relatively low network activity (e.g., when an aircraftis not in flight, at night, etc.).

In some examples of communications environments 100, 200 or 300,distributed delivery networks 130-b or 130-c may include one or morehigh-reliability or shock and vibration tolerant storage nodes. Forexample, a subset of distributed storage devices 140 may be configuredto include solid-state storage media (e.g., SSD, etc.). A distributedstorage device 140 with high-reliability or shock and vibration tolerantstorage may operate as the leader device (e.g., manage message flow,manage redundancy of messages, maintain the index of storage messagesfor the distributed delivery networks 130, etc.). In some embodiments,the high-reliability or shock and vibration tolerant device may be usedto store the most requested messages (e.g., with or without redundancyin the other distributed storage devices 140). In some examples, thenetwork gateway device 150 may include the high-reliability storagedevice and may operate as the leader device for the distributed deliverynetwork 130. Additionally or alternatively, distributed storage devices140 may include a combination of a rotating disk storage device andsolid-state storage (e.g., hybrid drive, etc.). The solid-state storagemay be used for maintaining the index of stored messages, or for themost highly requested content, in some cases.

In some examples of communications environments 100, 200 or 300,messages may be pre-fetched from a rotating disk storage device ofdistributed storage devices 140 and buffered in solid-state storage(e.g., RAM memory, SSD, etc.). For example, streaming traffic may beorganized as an ordered list of messages such that when a streamingmedia file is requested, the messages that make up the file willgenerally be transferred in order (e.g., subject to packet flow andacknowledgement, etc.). Thus, for streaming media programming,distributed delivery network 130 can predict that the next messages inthe ordered list for the streaming media will likely be requested (e.g.,unless the user pauses or stops the stream, etc.). Turbulence or otherevents that cause shock may typically last from a few seconds to a fewminutes. Therefore, distributed delivery network 130 may pre-fetchmessages corresponding to several minutes or more of a requestedstreaming media file from the rotating disk storage device of adistributed storage device 140 and store the messages in the solid-statestorage (e.g., in a high reliability node of the distributed deliverynetwork, the solid state storage of a hybrid drive, etc.). If aturbulence event occurs, the distributed delivery network 130 cancontinue to provide the buffered messages even when the rotating diskstorage device is disabled for protection. While the streaming mediaplayer at the user device may have its own buffer, the distributeddelivery network 130 may pre-fetch a longer time-window for thestreaming media programming, up to and including the full streamingmedia file. The distributed delivery network 130 may maintain thepre-fetched messages for a predetermined amount of time, or until anevent occurs (e.g., the solid-state storage buffer is full with activemessage flows, the aircraft lands, etc.).

FIG. 4 shows a diagram of an example distributed storage device 140-dfor a distributed delivery network in accordance with various aspects ofthe disclosure. Distributed storage device 140-d includes rotating diskstorage device (e.g., HDD, etc.) 410, control circuit 415, environmentalsensor 420, and network interface 425. The components of distributedstorage device 140-d may be included within a physical housing 440 thatconnects to a power bus 450 and network signaling 455 (e.g., wired orwireless, etc.). Each of these components may be in communication witheach other.

The control circuit 415 may manage operation of the distributed storagedevice 140-d for operation in a distributed delivery network. Forexample, the control circuit 415 may manage operational states of thedistributed storage device 140-d, monitor sensor data from theenvironmental sensor 420, and manage communication with a networkgateway device, other distributed storage devices, or other devices(e.g., communication devices 115 of FIG. 1) via network interface 425.Network interface 425 may implement wired network interfaces (e.g.,Ethernet, Fibre Channel, etc.) and/or wireless network interfaces (e.g.,IEEE 802.11 compliant interfaces, etc.).

Rotating disk storage devices may have maximum operating specificationsfor vibration and shock, which are typically specified in accelerationwithin a given frequency range (vibration) or over a given time period(shock). Environmental sensor 420 may include an inertial measurementsensor (e.g., accelerometer, etc.), which may indicate when thedistributed storage device 140-d is experiencing high levels ofvibration or shock. The control circuit 415 may filter the accelerometerdata to determine the acceleration, velocity, or displacement, and maycompare these values with one or more thresholds to determine if thevibration or shock experienced by the distributed storage device 140-dexceeds operating thresholds for the rotating disk storage device 410,which may be considered adverse environmental conditions for therotating disk storage device 410. Additionally or alternatively,environmental sensor 420 may include other sensors such as a gyroscopeor a temperature sensor. The control circuit 415 may monitor data fromthese sensors to determine if environmental conditions (e.g.,orientation, temperature, etc.) exceed operational tolerances. Thecontrol circuit 415 may transition the distributed storage device 140-dfrom an active state to a standby state based on detection of adverseoperating conditions. Additionally or alternatively, the control circuit415 may receive information related to an impending adverse operatingcondition for the rotating disk storage device 410 and may transitionthe distributed storage device from the active state to the standbystate based on the impending adverse operating condition. For example,the control circuit 415 may receive information from an aircraft databus, which may include weather information indicating that impendingturbulence is in the flight path. Additionally or alternatively,distributed storage devices may communicate local environmentalconditions from different locations within the aircraft, which mayindicate that vibrations or turbulence is increasing and an adverseenvironmental condition is impending.

FIG. 5 shows an example operational state diagram 500 for a distributedstorage device 140 in accordance with various aspects of the disclosure.For example, operational state diagram 500 may illustrate operationalstates for distributed storage device 140-d of FIG. 4. The operationalstates of the distributed storage device 140-d may include an initialpower on state 505, an active state 510, a standby state 515, an errorstate 520, and an exit state 525. Transitions between states may bemanaged by the control circuit 415. The distributed storage device 140-dmay start in the power on state 505 when powered on. From the power onstate 505, the distributed storage device 140-d may transition to theactive state and announce entry of the distributed storage device 140-dfor operation on a distributed delivery network such as distributeddelivery networks 130 of FIGS. 1-3.

In the active state 510, access to the rotating disk storage device 410is enabled. For example, the distributed storage device 140-d mayreceive messages for storage via the network interface 425 in the activestate and store the messages in the rotating disk storage device 410.The distributed storage device 140-d may also receive requests forstored messages in the active state and may retrieve and deliver thestored messages in response to the requests.

In the active state, the control circuit 415 may monitor the sensor datafrom environmental sensor 420 and determine when environmentalconditions for the distributed storage device 140-d are adverse foroperation of the rotating disk storage device 410. If, while in theactive state 510, the control circuit 415 detects an adverse operatingcondition for the rotating disk storage device 420, the control circuit415 may transition the distributed storage device 140-d to the standbystate 515. The control circuit 415 may also announce (e.g., broadcast,etc.) that the distributed storage device 140-d is entering the standbystate 515 and is no longer available for storing or delivering messages.

When the distributed storage device 140-d is in the standby state 515,access to the rotating disk storage device 410 is disabled and therotating disk storage device 410 may be configured in a protected state.For example, the rotating disk storage device 410 may be configured in aparked media or deactivated state, or may be unpowered. In someexamples, the distributed storage device 140-d may include a diskbuffer, which may be solid state memory (e.g., RAM, etc.). When enteringthe standby state 515, the distributed storage device 140-d may continueto deliver buffered messages based on requests received in the activestate 510. Additionally or alternatively, if the distributed storagedevice 140-d includes a hybrid drive, the distributed storage device140-d may continue to allow access to the solid-state storage of thehybrid drive in the standby state 515.

If an exception (e.g., recoverable error, etc.) occurs while in theactive state 510 or the standby state 515, the distributed storagedevice 140-d transitions to the error state 520, where error recoverymay be attempted. If error recovery in the error state 520 issuccessful, the distributed storage device 140-d transitions back to thestandby state 515. If error recovery in the error state 520 isunsuccessful, the distributed storage device 140-d transitions to theexit state 525. Upon transitioning from the active state 510 to theerror state 520, the distributed storage device 140-d may announce thatthe distributed storage device 140-d is no longer available for storingor delivering messages. The distributed storage device 140-d may alsotransition to the error state 520 if an unrecoverable error occurs whilein the active state 510 or the standby state 515. In this instance, thedistributed storage device 140-d may also announce that the distributedstorage device 140-d is no longer available for storing or deliveringmessages.

In the standby state 515, the control circuit 415 may continue tomonitor the sensor data from environmental sensor 420 and determine whenenvironmental conditions for the distributed storage device 140-d aresafe for operation. When safe operating conditions for the rotating diskstorage device 410 are detected, the control circuit 415 may transitionthe distributed storage device 140-d back to the active state 510. Thecontrol circuit 415 may also announce (e.g., broadcast, etc.) that thedistributed storage device 140-d is entering the active state 510 and isagain available for storing or delivering messages.

Returning to FIG. 4, the distributed storage device 140-d may include apower supply 405, which may be coupled with a power bus 450 of a mobileenvironment, and may convert a supply voltage of the power bus 450 tointernal voltages used by components of the distributed storage device140-d. The power supply 405 may also provide robustness to power surgesand the capability of replacing the distributed storage device 140-dwithout disrupting the power bus 450 or damaging the rotating diskstorage device 410.

The housing 440 may be configured to orient the rotating disk storagedevice in a horizontal orientation as installed, and may includevibration dampening bushings between the housing 440 and brackets of themobile environment 105. The housing may be configured with fittings thatcouple with the brackets and a release lever to release the fitting fromthe bracket. The power supply 405 may be configured to be connected tothe power bus 450 while the power bus 450 is live (e.g., hot swappable).

As discussed above, the distributed storage devices 140 of distributeddelivery networks 130 may operate according to a leader/followertopology for message flow management where one distributed storagedevice 140 acts as a leader device and the other distributed storagedevices 140 act as follower devices. The leader device may monitor theoperational states of follower devices and maintain a device state tablethat indicates which distributed storage devices 140 are in the activestate and available for storing and retrieving messages, and whichdistributed storage devices 140 are unavailable (e.g., in the standbystate or having left the distributed delivery network). The leaderdevice may also manage storage of messages in the distributed storagedevices 140 (e.g., manage redundancy of messages, etc.) and maintain anindex of messages stored in the distributed storage devices 140 forretrieval. The leader device may broadcast changes in the device statetable and message index, and follower devices may each maintain aseparate copy of the device state table and message index. Thus, if afollower device becomes the leader (e.g., based on consensus election orif the leader enters the standby state, etc.), the new leader will haveupdated copies of the device state table and message index.

FIG. 6 shows a flow diagram 600 of an example message flow for capacityenhancement of network access service in accordance with various aspectsof the disclosure. Flow diagram 600 illustrates message flow between anetwork gateway device 150-d, distributed storage devices 140-d-1 and140-d-n of distributed delivery network 130-d, and communication devices115. While network gateway device 150-d may provide network accessservice for a number of communication devices 115, only communicationdevices 115-a and 115-b are shown in flow diagram 600 for clarity. Flowdiagram 600 may illustrate, for example, message flow in thecommunications environments 100, 200, or 300 of FIGS. 1-3.

Communication device 115-a may send a request 605 for message A. MessageA may be, for example, a file or object that is part of video streamingprogramming (e.g., HTTP live streaming (HLS) file, etc.) requested froma content server of a network (e.g., network 120 of FIGS. 1-3). Thenetwork gateway device 150-d may send a query 610 to distributeddelivery network 130-d to see if message A has been stored in thedistributed delivery network 130-d.

Distributed storage device 140-d-1 may currently be acting as the leaderdevice for distributed delivery network 130-d. In some examples,distributed storage device 140-d-1 may identify itself as the leaderdevice to network gateway device 150-d and network gateway device 150-dmay communicate query 610 directly to distributed storage device140-d-1. Alternatively, network gateway device 150-d may broadcast query610 to distributed delivery network 130-d (e.g., over a SAN, etc.), andthe leader device (e.g., distributed storage device 140-d-1) may respondfor the distributed delivery network 130-d.

Distributed storage device 140-d-1 may determine (e.g., based on themessage index for distributed delivery network 130-d) that message A isnot stored in distributed delivery network 130-d. Distributed storagedevice 140-d-1 may send an indication 615 to network gateway device150-d that message A is not stored in distributed delivery network130-d. Network gateway device 150-d may then retrieve message A over ashared communications link (e.g., shared communication links 110 ofcommunications environments 100, 200, or 300 of FIGS. 1-3) at 620, andmay deliver message A to communications device 115-a at 625.

Network gateway device 150-d may also send message A to distributeddelivery network 130-d at 630. Acting as the leader device fordistributed delivery network 130-d, distributed storage device 140-d-1may determine if message A should be stored in distributed deliverynetwork 130-d. If distributed storage device 140-d-1 determines thatmessage A should be stored at 635, distributed storage device 140-d-1may send message A to distributed storage device 140-d-n at 640 and mayupdate the message index accordingly. Determining whether message Ashould be stored at 635 may be based on a message type for message A(e.g., determining that message A is a type of message for which a localcopy can be delivered in response to a subsequent request, etc.).

Subsequently, communication device 115-b may send a request 645 formessage A. The network gateway device 150-d may send a query 650 todistributed delivery network 130-d to see if message A has been storedin the distributed delivery network 130-d. At 655, distributed storagedevice 140-d-1 may locate message A in distributed storage device140-d-n. In some cases, a content provider may also be involved indetermining that a message is stored in the distributed delivery network130-d. For example, where a content provider has pre-loaded or pushedcontent to the distributed delivery network 130-d, the content providermay send an index to the content in response to the request from thecommunication device 115-b, and distributed storage device 140-d-1 maylocate the content based on the content provider index.

Distributed storage device 140-d-1 may determine that distributedstorage device 140-d-n is available for message retrieval (e.g., in theactive state, etc.) and request message A from distributed storagedevice 140-d-n at 660. Message A may be received from distributedstorage device 140-d-n at 665. Distributed storage device 140-d-1 mayprovide message A to network gateway device 150-d at 670, and networkgateway device 150-d may provide message A to communication device 115-bat 675, which may appear to communication device 115-b as having comefrom the content server from which message A was requested.

Distributed storage device 140-d-1 may also determine redundancy formessage A at 655. Determining redundancy for message A at 655 mayinclude determining how many copies of message A should be stored indistributed delivery network 130-d and where to store the copies.Message redundancy may be performed according to a storage policy thatis based on frequency of requests for message A. For example,distributed storage device 140-d-1 (as the leader device) may comparethe number of requests (e.g., over a given time, etc.) for message Aagainst one or more thresholds to determine the redundancy of storage ofmessage A in distributed delivery network 130-d. For example, formessages that have been requested only once, a single copy of themessage may be stored in distributed delivery network 130-d (e.g., noredundancy). For messages that have been requested a first number oftimes greater than a first threshold, two instances of the message maybe stored in two different locations (e.g., on different distributedstorage devices 140-d, etc.) in distributed delivery network 130-d.Additional thresholds may defined and associated with additional levelsof redundancy, up to and including storing the message on eachdistributed storage device 140-d.

FIG. 7 shows a flow diagram 700 of an example message flow for capacityenhancement of network access service in accordance with various aspectsof the disclosure. Flow diagram 700 illustrates message flow between anetwork gateway device 150-e, distributed storage devices 140-e-1 and140-e-n of distributed delivery network 130-e, and communication devices115. While network gateway device 150-e may provide network accessservice for a number of communication devices 115, only communicationdevices 115-c and 115-d are shown in flow diagram 700 for clarity. Flowdiagram 700 may illustrate, for example, message flow in thecommunications environments 100, 200, or 300 of FIGS. 1-3.

Block 705 of flow diagram 700 may include message flow actionscorresponding to steps 605 to 640 of flow diagram 600 of FIG. 6. Forexample, block 705 may include one or more requests for message A fromcommunication devices 115, and message A may be stored at least indistributed storage device 140-e-n.

Subsequently, communication device 115-d may send a request 745 formessage A. The network gateway device 150-e may send a query 750 todistributed delivery network 130-e to see if message A has been storedin the distributed delivery network 130-e. At 755, distributed storagedevice 140-e-1 (e.g., acting as leader device) may locate message A indistributed storage device 140-e-n at 755. Distributed storage device140-e-1 may also determine redundancy for message A at 755, as describedabove with reference to block 655 of FIG. 6.

Distributed storage device 140-e-1 may determine that distributedstorage device 140-e-n is available for message retrieval (e.g., in theactive state, etc.) and may provide a proxy address A′ 760 for message Aat distributed storage device 140-e-n. Network gateway device 150-d maysend a redirect message 765 for message A to communication device 115-d,which may then request message A from distributed storage device 140-e-nusing the proxy address A′ at 770. Distributed storage device 140-e-nmay provide message A to communication device 115-d at 775.

While FIGS. 6 and 7 illustrate one of the distributed storage devices140 acting as the leader device for distributed delivery networks 130,the network gateway device 150 may instead act as the leader device. Forexample, the network gateway device 150 may monitor the operationalstates of the distributed storage devices 140, manage storage andredundancy of messages in the distributed storage devices 140 andmaintain an index of messages stored in the distributed storage devices140 for retrieval.

As discussed above, distributed storage devices 140 may broadcast statusmessages to the other distributed storage devices 140 in the distributeddelivery network 130. For example, distributed storage devices 140 mayannounce entry into (e.g., upon power-on or error recovery) and exitfrom (e.g., unrecoverable error conditions, etc.) the distributeddelivery network 130 and may periodically broadcast a status or“heartbeat” message that confirms the device is operational. Distributedstorage devices 140 may also broadcast other information such as badsectors, environmental conditions, and the like.

The leader device of a distributed delivery network (e.g., thedistributed delivery networks 130 of FIG. 1-3, 6 or 7) may maintain adevice state table with current operational states of all distributedstorage devices 140. FIG. 8 shows a diagram of an example device statetable 800 in accordance with various aspects of the disclosure. Devicestate table 800 includes entries 805 for each distributed storage device810 in a distributed delivery network (e.g., the distributed deliverynetworks 130 of FIG. 1-3, 6 or 7). For each device 810, the device statetable 800 includes device status information 820 and may include otherinformation 830 such as bad sectors for each device.

The leader device may receive broadcast status information (e.g., statusmessages, heartbeat messages, etc.) from each distributed storage device140 and update device state table 800 accordingly. The leader may then(e.g., periodically, upon update, etc.) broadcast the values from devicestate table 800, which may be mirrored in the follower devices in casethe leader becomes unavailable and one of the follower devices becomesthe leader.

As discussed above, the leader device may be selected in a variety ofways. For example, leader priority may be statically defined, or theleader may dynamically selected using peer-to-peer communication betweendistributed storage devices 140. In some examples, the leader device iselected by a consensus operation of the distributed storage devices 140currently in the active state.

FIG. 9 shows an example dynamic leader selection state diagram 900 for adistributed delivery network in accordance with various aspects of thedisclosure. Dynamic leader selection state diagram 900 may be used, forexample, by a distributed storage device 140 operating on thedistributed delivery networks 130 of FIG. 1-3, 6 or 7.

At initial startup, the distributed storage device 140 may beinitialized as a follower 905. Election cycles may be performed on aperiodic basis. Upon the next election cycle, the follower 905 may be acandidate 910 for leader. The election may be conducted according to aconsensus algorithm (e.g., Paxos, Multi-Paxos, Raft, etc.). If thecandidate 910 is elected by the consensus algorithm, the candidate willbe the leader 915 until the leader 915 discovers a new leader andreturns to being a follower 905. If the leader becomes unavailable(e.g., transitions to the standby state, etc.) the leader may force anelection, removing itself from being a candidate 910. In some examples,the consensus algorithm may result in a statistical sharing of theoperations associated with being the leader device. Because the leaderdevice may see heavier use than other devices, multiplexing the leaderdevice operations may reduce failure rates for the components of thedistributed storage devices 140 (e.g., HDD failure rates, etc.).

FIG. 10 illustrates a block diagram 1000 of a control circuit 415-a fora distributed storage device in accordance with various aspects of thedisclosure. The control circuit 415-a may illustrate, for example,aspects of control circuit 415 of FIG. 4. The control circuit 415-aincludes device state manager 1005, sensor monitor 1010, communicationsmanager 1015, and disk controller 1020. Each of these components may bein communication with each other, directly or indirectly.

The sensor monitor 1010 may perform functions associated with receivingsensor data and processing the sensor data (e.g., filtering, comparingsensor data with thresholds, etc.). The sensor monitor 1010 may provideinformation to the device state manager 1005 indicating whether theenvironmental conditions are safe or adverse for a rotating disk storagedevice of the distributed storage device.

Device state manager 1005 may manage operational states for thedistributed storage device. For example, the device state manager 1005may receive information from the sensor monitor 1010 relating to thecurrent environmental conditions of the distributed storage device. Ifthe sensor monitor 1010 indicates that the current environmentalconditions are adverse for operation of a rotating disk storage deviceof the distributed storage device, the device state manager 1005 maytransition the distributed storage device from an active state to astandby state. The device state manager 1005 may send a notification ofthe state transition (e.g., via communications manager 1015). The devicestate manager 1005 may perform other operations for device statetransitions described above with reference to FIG. 5.

The disk controller 1020 may perform operations associated with storingand retrieving messages from the rotating disk storage device.Additionally, the disk controller 1020 may perform operations forsecuring the rotating disk storage device if the distributed storagedevice enters the standby state because of adverse environmentalconditions. For example, when the distributed storage device enters thestandby state, the disk controller 1020 may configure the rotating diskstorage device in a protected state such as a parked media state, adeactivated state, or an unpowered state.

FIG. 11 illustrates a block diagram 1100 of a control circuit 415-b fora distributed storage device in accordance with various aspects of thedisclosure. The control circuit 415-b may illustrate, for example,aspects of control circuits 415 of FIG. 4 or FIG. 10. The controlcircuit 415-b includes device state manager 1005-a, sensor monitor1010-a, communications manager 1015-a, disk controller 1020-a, followercontroller 1125, message index manager 1130, and leader controller 1135.Each of these components may be in communication with each other,directly or indirectly. Device state manager 1005-a, sensor monitor1010-a, communications manager 1015-a, and disk controller 1020-a mayperform the functions of device state manager 1005, sensor monitor 1010,communications manager 1015, disk controller 1020 of FIG. 10,respectively.

Follower controller 1125 may control functions related to device statetable and message index updates when the distributed storage device isoperating as a follower device in the distributed delivery network. Forexample, follower controller 1125 may receive updates to the devicestate table and message index and update the corresponding entries(e.g., via message index manager 1130, etc.). Follower controller 1125may also manage participation of the distributed storage device in thedynamic selection of leader devices (e.g., consensus election process asdescribed above with reference to FIG. 9, etc.).

Leader controller 1135 may control functions related message flow andmaintaining the operational state table and message index when thedistributed storage device is operating as the leader device in thedistributed delivery network. For example, leader controller 1135 mayinclude message flow manager 1145, which may receive requests formessages (e.g., from a network gateway device 150, etc.), determine ifthe requested messages are stored in the distributed delivery network(e.g., based on the message index, etc.), and retrieve and deliverstored messages in response to the requests. Additionally oralternatively, message flow manager 1145 may forward a proxy address ofthe stored messages for redirection to the stored messages.

Leader controller 1135 may also monitor for periodic status messagesfrom distributed storage devices of the distributed delivery network andupdate the operational state table if any of the distributed storagedevices have not sent the periodic status messages or have otherwiseindicated themselves as unavailable (e.g., transition to standby mode,etc.). Additionally, leader controller 1135 may update the message indexto indicate that instances of messages stored at unavailable storagenodes are unavailable.

Leader controller 1135 may include redundancy manager 1140, which maymanage redundancy for messages in distributed delivery network. Forexample, if a number of requests for a given stored message exceeds athreshold, redundancy manager 1140 may increase redundancy for themessage. Leader controller 1135 may forward the message to a differentdistributed storage device for redundant storage of the message.Redundancy manager 1140 may determine redundancy levels using multiplethresholds based on the non-uniform probability density of messages. Forexample, redundancy manager 1140 may determine a storage policy forredundancy of messages by optimizing an information rate provided by thedistributed delivery network based on the non-uniform probabilitydensity of messages and parameters of the distributed delivery network(e.g., number of distributed storage devices, total storage, reliabilitymetrics of the distributed storage devices, etc.). Alternatively,redundancy manager 1140 may determine the storage policy as a normalizedcurve fit (e.g., linear, log-linear, polynomial) of the non-uniformprobability density of messages or by using heuristic approachesproviding a quasi-optimal information rate (e.g., gradient ascent, montecarlo, simulating annealing, etc.).

The components and modules of control circuits 415 of FIG. 4, 10 or 11may, individually or collectively, be implemented with one or moreApplication Specific Integrated Circuits (ASICs) adapted to perform someor all of the applicable functions in hardware. Alternatively, thefunctions may be performed by one or more other processing units (orcores), on one or more integrated circuits. In other embodiments, othertypes of integrated circuits may be used (e.g., Structured/PlatformASICs, Field Programmable Gate Arrays (FPGAs) and other Semi-CustomICs), which may be programmed in any manner known in the art. Thefunctions of each unit may also be implemented, in whole or in part,with instructions embodied in a memory, formatted to be executed by oneor more general or application-specific processors.

FIG. 12 shows a simplified diagram of an example satellitecommunications system 1200 which may implement capacity enhancementusing a distributed delivery network in accordance with various aspectsof the disclosure. The satellite communication system 1200 includes asatellite 1205 (or multiple satellites 1205), a ground station 1215, aground station antenna system 1210, and a network gateway device 150-f.In operation, the satellite communication system 1200 provides networkaccess service via the network gateway device 150-f to multiplecommunication devices 115. For example, the satellite communicationsystem 1200 may provide for two-way communications between the networkgateway device 150-f and a network 120 via the satellite 1205 and theground station 1215. The communication devices 115 may be connected tothe network gateway device 150-f via one or more access points 165-f(e.g., WAPs 165, etc.).

The satellite or satellites 1205 may include any suitable type ofcommunication satellite. In some examples, some or all of the satellitesmay be in geostationary orbits. In other examples, any appropriate orbit(e.g., medium earth orbit (MEO), low earth orbit (LEO), etc.) forsatellite 1205 may be used. In one embodiment, the satellite 1205operates in a multi-beam mode, transmitting a number (e.g., typically20-150, etc.) of spot beams each directed at a different region of theearth. This can allow coverage of a relatively large geographical areaand frequency re-use within the covered area. Spot beams forcommunication with subscribers may be called service beams while spotbeams for communication with gateways such as ground station 1215 may becalled feeder beams. In embodiments, the service beams are fixedlocation spot beams, meaning that the angular beam width and coveragearea for each service beam does not intentionally vary with time.

The ground station 1215 sends and receives signals to and from thesatellite 1205 via communication link 1240 using the ground stationantenna system 1210. The ground station antenna system 1210 may betwo-way capable and designed with adequate transmit power and receivesensitivity to communicate reliably with the satellite 1205. The groundstation 1215 is connected to the one or more networks 120, which may bethe networks discussed with reference to FIGS. 1-3.

The network gateway device 150-f may use an antenna 1240 to communicatesignals with the satellite 1205 via the communication link 110-d. Theantenna 1240 may be mounted to an elevation and azimuth gimbal whichpoints the antenna 1240 (e.g., actively tracking) at satellite 1205. Thesatellite communications system 1200 may operate in the InternationalTelecommunications Union (ITU) Ku, K, or Ka-bands, for example from 17.7to 21.2 Giga-Hertz (GHz). Alternatively, satellite communications system1200 may operate in other frequency bands such as C-band, X-band,S-band, L-band, and the like. As illustrated in FIG. 12, network gatewaydevice 150-f and antenna 1240 are mounted on an aircraft 1260. However,network gateway device 150-f and antenna 1240 may be used in otherapplications besides onboard the aircraft 1260, such as onboard boats,vehicles, or a stationary location where network access service isdesired (e.g., a business, a school, etc.), in some cases.

The satellite communications system 1200 may also include one or moresubscriber terminals 1230, which may also be provided network accessservice via satellite 1205 and ground station 1215. Each subscriberterminal 1230 is located within at least one service beam and is capableof two-way communication with the satellite 1205 via an antenna 1225.Each subscriber terminal 1230 may be connected with (e.g., may providenetwork access service for) one or more customer devices 1235 (e.g.,desktop computers, laptops, set-top boxes, smartphones, tablets,Internet-enabled televisions, and the like). These customer devices 1235may also be known as customer premises equipment (CPE).

Typically, satellite communications system 1200 may have a fixedcapacity based on a system bandwidth and a number of spot beams forfrequency re-use. While that capacity may be allocated to subscriberterminals 1230 and mobile devices 115 in a variety of ways, it may notalways be possible to provide a high data rate to all subscriberterminals 1230 and mobile devices 115 at the same time via signalstransmitted over the satellite links 110-d and 1250.

In embodiments, the satellite system 1200 is configured to provide ahigh-quality network access experience to mobile devices 115 byincreasing the capacity of the communications system 1200 using adistributed delivery network 130-f as described above. The distributeddelivery network 130-f may include multiple distributed storage devices140 (e.g., distributed storage devices 1404-1, 140-f-2, 140-f-n, etc.)that store messages requested by mobile devices 115 for delivery toother mobile devices in response to subsequent requests. The distributedstorage devices 140 may be connected to the network gateway device 150-fand each other via a network 155-f (e.g., SAN 155-f, etc.). Thedistributed delivery network 130-f may perform the functions describedabove for distributed delivery networks 130 of FIG. 1-3, 6 or 7, whichare not repeated here for the sake of brevity.

As discussed above, distributed storage devices 140 may be distributedthroughout a mobile environment such as aircraft 1260. FIG. 13 shows adiagram 1300 illustrating example locations for installation ofdistributed storage devices 140 on an aircraft 1260-a in accordance withvarious aspects of the disclosure. In diagram 1300, distributed storagedevices 140-g-1 and 140-g-2 are located in the roof of the cabin of theaircraft 1260-a, above the interior paneling, which is generallyremovable for access. Distributed storage devices 140-g-1 and 140-g-2may be located near WAP 165-g, and may be connected to a network gatewaydevice 150 (not shown) on aircraft 1260-a via wired or wirelessconnections (e.g., via WAP 165-g, etc.). For simplicity diagram 1300illustrates only two distributed storage devices 140-g, however, itshould be understood that additional distributed storage devices 140-gmay be distributed in other locations throughout aircraft 1260-a.

In some cases, locating distributed storage devices 140 in variouslocations throughout aircraft 1260-a may provide for higher tolerance ofenvironmental conditions such as turbulence because different portionsof aircraft 1260-a may experience turbulence in different manners. Forexample, as an aircraft experiences shock, pitch, or yaw movement,different portions of the aircraft have different trajectories. Inaddition, an aircraft fuselage may experience flex, which may result indifferent levels of shock or vibration at different locations within theaircraft cabin. By distributing the distributed storage devices 140-gthroughout the aircraft 1260-a where the local environmental conditionscan vary significantly, the capacity enhancement provided by the networkof distributed storage devices 140-g can be relatively robust. In otherwords, although the capacity enhancement can change over time asindividual distributed storage devices 140-g autonomously transitionbetween active and standby states, the variance in local environmentalconditions reduces the likelihood that all or most of them willtransition into the standby state at the same time.

FIG. 14 shows a diagram 1400 illustrating alternative example locationsfor installation of distributed storage devices 140 on an aircraft1260-b in accordance with various aspects of the disclosure. In diagram1400, distributed storage device 140-h is located underneath seat 1410in the cabin of aircraft 1260-b. Distributed storage device 140-h may beconnected to a network gateway device 150 (not shown) on aircraft 1260-bvia wired or wireless connections (e.g., via a WAP 165, etc.). Forsimplicity, diagram 1400 illustrates only one distributed storagedevices 140-h, however, it should be understood that additionaldistributed storage devices 140-g may be distributed in similarlocations throughout aircraft 1260-b. In addition, a system may use theillustrated locations for distributed storage devices 140 of diagrams1300 and 1400 in combination, as well as additional locations within anaircraft 1260.

In some embodiments, distributed storage devices 140 includequick-release features to allow for replacement of non-functionaldistributed storage device 140 (e.g., due to failure of the rotatingdisk storage device, etc.). For example, the distributed storage devices140 may include a housing with a fitting mounted to the housing forcoupling with an external bracket mounted to the aircraft. A releaselever may be coupled with the fitting to release the fitting from theexternal bracket. The distributed delivery network 130 may indicate(e.g., via a network gateway device 150, etc.) distributed storagedevices 140 that are to be replaced by sending messages to a servicecenter. A technician may retrieve the information and replace thedistributed storage devices 140 when servicing the aircraft. Thenon-functional distributed storage devices 140 may be refurbished (e.g.,by installing a new rotating disk storage device, etc.) for future use.

FIG. 15 shows a flowchart diagram of an example method 1500 for capacityenhancement of network access service in accordance with various aspectsof the disclosure.

At block 1505 of method 1500, a distributed storage device of acommunications system may be provided. The communications system mayinclude, for example, multiple distributed storage devices coupled to anetwork gateway device. For example, the distributed storage devices 140may be implemented in a distributed delivery network 130 as describedabove with reference to FIG. 1-3, 6, 7 or 12.

At block 1510, the distributed storage device may detect whether anadverse operating condition for a rotating disk storage device of thedistributed storage device is present based on a sensor signal from asensor of the distributed storage device indicating a characteristic ofan environment of the distributed storage device. If an adverseoperating condition is not present (e.g., the operating conditions aredetermined to be safe for the rotating disk storage device), thedistributed storage device may stay in or transition to the active state1515.

In the active state 1515, the distributed storage device may provideaccess to the rotating disk storage device for operations of thedistributed delivery network. For example, at block 1520 a message maybe received for storage in the distributed storage device and thedistributed storage device may store the message at block 1525. Thedistributed storage device may receive a request for the stored messageat block 1530 and may retrieve and provide the message in response tothe request at block 1535. The request for the message received at block1530 may, for example, be for redundancy of storage within otherdistributed storage devices of the distributed delivery network (e.g.,based on a request from a leader device or the network gateway device,based on a frequency of requests for the given stored message, etc.).

The distributed storage device may continue to monitor the sensor signalin the active state 1515 at block 1540, and determine whether adverseoperating conditions exist at block 1510. Based on detection of anadverse operating condition at block 1510, the distributed storagedevice may transition to the standby state 1545. Upon transitioning tothe standby state 1545, the distributed storage device may transmit(e.g., broadcast, etc.) an indication that the distributed storagedevice is unavailable to other devices of the distributed deliverynetwork.

In the standby state 1545, the distributed storage device may preventaccess to the rotating disk storage device at block 1550. For example,the distributed storage device may configure the rotating disk storagedevice in a protected state (e.g., parked media state, deactivated,unpowered, etc.). In the standby state 1545, the distributed storagedevice may continue to monitor the sensor signal at block 1555, anddetermine whether the adverse operating conditions still exist at block1510.

FIG. 16 shows a flowchart diagram of an example method 1600 for capacityenhancement of network access service in accordance with various aspectsof the disclosure. The method may be performed, for example, by adistributed storage device 140 as described above with reference toFIGS. 1-15.

At block 1605, an election may determine a leader for a distributeddelivery network. The consensus election may be performed periodically,be event driven (e.g., the leader becomes unavailable, etc.), and may beconducted according to a consensus algorithm (e.g., Paxos, Multi-Paxos,Raft, etc.).

If, at block 1610, the distributed storage device 140 determines that itis the leader device as a result of the election at block 1605, thedistributed storage device 140 may perform functions associated with theleader device at blocks 1615-1655. For example, the leader device mayidentify a new message for storage in the distributed delivery networkat block 1615 and store the message in one of the distributed storagedevices 140 at block 1620. The leader device may receive a request for astored message at block 1625, and may locate the requested storedmessage at block 1630. The leader device may retrieve the message, ormay provide a proxy address for the requested stored message at block1630, in some cases.

At block 1635, the leader device may determine message redundancy forthe message. Determining redundancy for the message may includedetermining how many copies of the message should be stored in thedistributed delivery network 130 and where to store the copies.Determining the redundancy may be based on a frequency of requests forthe message, and may include multiple different levels of redundancycorresponding to multiple request thresholds as discussed above. Theleader device may send the stored message to additional distributedstorage devices based on the determined redundancy level.

After storing the message in one or more distributed storage devices atblocks 1620 or 1635, the leader device may update the message index atblock 1650. The leader device may broadcast updates to the message indexto the distributed storage devices for maintenance of back-up copies ofthe message index.

The leader device may monitor the status of other distributed storagedevices at block 1640. For example, the leader device may monitor forstatus messages from the follower devices and update an operationalstate table including entries and status conditions (e.g., active orstandby state, etc.) of the other distributed storage devices. Theleader device may also track other information such as bad sectors foreach of the distributed storage devices. The leader device may broadcastthe operational state table to the distributed storage devices formaintenance of back-up copies of the operational state table. The leaderdevice may determine that a new election cycle is occurring at block1655 and return to block 1610 to determine if it is still the leaderdevice.

If, at block 1610, the distributed storage device is not the leaderdevice for the current election cycle, the distributed storage devicemay perform the functions of a follower device in blocks 1660-1665. Forexample, the follower device may receive broadcast information at block1660 including updates for the message index and operational statetable, and may maintain a copy of the message index and operationalstate table. The follower device may determine that a new election cycleis occurring at block 1665 and return to block 1610 to determine if itwill become the leader device. As a follower device, the distributedstorage device may continue to perform the functions for sensormonitoring, state management, message storage, and message retrievaldescribed with respect to FIG. 15.

It should be noted that the methods, systems and devices discussed aboveare intended merely to be examples. It must be stressed that variousembodiments may omit, substitute, or add various procedures orcomponents as appropriate. For instance, it should be appreciated that,in alternative embodiments, the methods may be performed in an orderdifferent from that described, and that various steps may be added,omitted or combined. Also, features described with respect to certainembodiments may be combined in various other embodiments. Differentaspects and elements of the embodiments may be combined in a similarmanner. Also, it should be emphasized that technology evolves and, thus,many of the elements are exemplary in nature and should not beinterpreted to limit the scope of embodiments of the principlesdescribed herein.

Specific details are given in the description to provide a thoroughunderstanding of the embodiments. However, it will be understood by oneof ordinary skill in the art that the embodiments may be practicedwithout these specific details. For example, well-known circuits,processes, algorithms, structures, and techniques have been shownwithout unnecessary detail in order to avoid obscuring the embodiments.

Also, it is noted that the embodiments may be described as a processwhich is depicted as a flow diagram or block diagram. Although each maydescribe the operations as a sequential process, many of the operationscan be performed in parallel or concurrently. In addition, the order ofthe operations may be rearranged. A process may have additional stepsnot included in the figure. Processors may perform the necessary tasks.Features implementing functions may also be physically located atvarious positions, including being distributed such that portions offunctions are implemented at different physical locations.

Furthermore, embodiments may be implemented by hardware, software,firmware, middleware, microcode, hardware description languages, orcombinations thereof. When implemented in software, firmware, middlewareor microcode, the program code or code segments to perform the necessarytasks may be stored in a computer-readable medium such as a storagemedium. A computer-readable medium may include, for example, RAM, ROM,EEPROM, flash memory, CD-ROM or other optical disk storage, magneticdisk storage or other magnetic storage devices, or any other medium thatcan be used to carry or store desired program code means in the form ofinstructions or data structures and that can be accessed by ageneral-purpose or special-purpose computer, or a general-purpose orspecial-purpose processor.

As used herein, including in the claims, the term “and/or,” when used ina list of two or more items, means that any one of the listed items canbe employed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, and/or C, the composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination. Also, as usedherein, including in the claims, “or” as used in a list of items (forexample, a list of items prefaced by a phrase such as “at least one of”or “one or more of”) indicates a disjunctive list such that, forexample, a list of “at least one of A, B, or C” means A or B or C or ABor AC or BC or ABC (i.e., A and B and C).

Having described several embodiments, it will be recognized by those ofskill in the art that various modifications, alternative constructions,and equivalents may be used without departing from the spirit of theprinciples described herein. For example, the above elements may merelybe a component of a larger system, wherein other rules may takeprecedence over or otherwise modify the application of the principlesdescribed herein. Also, a number of steps may be undertaken before,during, or after the above elements are considered. Accordingly, theabove description should not be taken as limiting the scope of theinvention.

What is claimed is:
 1. A communications system comprising: a networkgateway device in a mobile environment, wherein the network gatewaydevice communicates messages for a plurality of user devices within themobile environment via a shared wireless link; a plurality ofdistributed storage devices coupled to the network gateway device,wherein at least two of the distributed storage devices of the pluralityof distributed storage devices are located at different locations withinthe mobile environment, a distributed storage device of the plurality ofdistributed storage devices comprising: a housing; a rotating diskstorage device within the housing; a network interface to supportcommunication with the network gateway device; a sensor to produce asensor signal indicating a characteristic of an environment external tothe housing; and a control circuit to detect an adverse operatingcondition for the rotating disk storage device based on the sensorsignal, and to transition the distributed storage device from an activestate to a standby state upon detection of the adverse operatingcondition, wherein: in the active state, the distributed storage deviceenables access of the rotating disk storage device to store a subset ofthe messages received via the network interface, to retrieve the storedsubset of the messages in response to requests received via the networkinterface, and to provide a given stored message of the stored subset ofthe messages for redundancy of storage within other distributed storagedevices of the plurality of distributed storage devices based on afrequency of requests for the given stored message; and in the standbystate, the distributed storage device prevents access to the rotatingdisk storage device, the control circuit further to determine that thedistributed storage device is operating as a leader device for theplurality of distributed storage devices, and to, while the distributedstorage device is operating as the leader device: determine a messageredundancy for the given stored message based on comparing the frequencyof requests for the given stored message to a threshold; and forward thegiven stored message for storing in one or more distributed storagedevices of the plurality of distributed storage devices based on themessage redundancy.
 2. The communications system of claim 1, wherein,upon transitioning from the active state to the standby state, thedistributed storage device transmits an indication that the distributedstorage device is unavailable.
 3. The communications system of claim 2,wherein the indication that the distributed storage device isunavailable is broadcast over a storage area network coupled with thenetwork gateway device and the plurality of distributed storage devices.4. The communications system of claim 1, wherein the transition of thedistributed storage device from the active state to the standby state isperformed independently of an operational state of at least one otherdistributed storage device of the plurality of distributed storagedevices.
 5. The communications system of claim 1, wherein, in thestandby state, the distributed storage device configures the rotatingdisk storage device in a protected state.
 6. The communications systemof claim 5, wherein the protected state comprises one or more of aparked media state, a deactivated state, or an unpowered state.
 7. Thecommunications system of claim 1, wherein, in the standby state, thecontrol circuit detects a safe operating condition for the rotating diskstorage device based on the sensor signal and transitions thedistributed storage device from the standby state to the active stateupon detection of the safe operating condition.
 8. The communicationssystem of claim 1, the control circuit further to, while the distributedstorage device is operating as the leader device: determine a change foran index of stored messages across the plurality of distributed storagedevices; and broadcast the change for the index to the plurality ofdistributed storage devices.
 9. The communications system of claim 8,the control circuit further to: determine that the distributed storagedevice is no longer operating as the leader device for the plurality ofdistributed storage devices; monitor broadcast messages for indicationsof changes to the index; and update the index upon based on receivedindications of changes to the index.
 10. The communications system ofclaim 8, the control circuit further to, while the distributed storagedevice is operating as the leader device: monitor for periodic statusmessages from the plurality of distributed storage devices; determinethat a second distributed storage device from the plurality ofdistributed storage devices is unavailable based upon not receiving aperiodic status message from the second distributed storage device; andflag one or more messages stored in the second distributed storagedevice as unavailable in the index.
 11. The communications system ofclaim 1, the control circuit further to, while the distributed storagedevice is operating as the leader device: receive a request for a firstmessage; determine that the first message is stored in a firstdistributed storage device of the plurality of distributed storagedevices; retrieve the first message from the first distributed storagedevice; and provide the first message in response to the request. 12.The communications system of claim 1, the control circuit further to,while the distributed storage device is operating as the leader device:receive a request for a first message; determine that the first messageis stored in a first distributed storage device of the plurality ofdistributed storage devices; and provide a proxy address of the firstmessage at the first distributed storage device in response to therequest.
 13. The communications system of claim 1, wherein the controlcircuit determines that the distributed storage device is operating asthe leader device for the plurality of distributed storage devices basedon a result of a consensus election.
 14. The communications system ofclaim 1, the control circuit further to: receive information related toan impending adverse operating condition for the rotating disk storagedevice; and transition the distributed storage device from the activestate to the standby state based on the impending adverse operatingcondition.
 15. The communications system of claim 1, the control circuitfurther to: detect a failure of the rotating disk storage device; andbroadcast an indication that the distributed storage device isunavailable based on the detected failure.
 16. The communications systemof claim 1, the control circuit further to: perform a periodicdiagnostic scan on the rotating disk storage device.
 17. Thecommunications system of claim 16, the control circuit further to:determine one or more storage locations of the rotating disk storagedevice failing the periodic diagnostic scan; identify one or moremessages stored in the one or more storage locations; broadcast anindication that the one or more messages are unavailable; and flag theone or more storage locations as unavailable for further use.
 18. Thecommunications system of claim 1, wherein the network interfacecomprises any of a wired networking interface, a wireless networkinginterface, or combinations thereof.
 19. The communications system ofclaim 1, the distributed storage device further comprising: a fittingmounted to the housing for coupling with an external bracket; a releaselever coupled with the fitting to release the fitting from the externalbracket.
 20. The communications system of claim 1, wherein the networkgateway device provides network access service for the mobileenvironment via the shared wireless link.
 21. The communications systemof claim 20, wherein the mobile environment comprises an aircraft, andthe plurality of distributed storage devices are located on theaircraft.
 22. The communications system of claim 20, wherein the sharedwireless link comprises a satellite communications link.
 23. Thecommunications system of claim 1, wherein the sensor comprises any of aninertial measurement sensor, a gyroscope, a temperature sensor, orcombinations thereof.
 24. A communications system comprising: a networkgateway device in a mobile environment, wherein the network gatewaydevice communicates messages for a plurality of user devices within themobile environment via a shared wireless link; a plurality ofdistributed storage devices coupled to the network gateway device,wherein at least two of the distributed storage devices of the pluralityof distributed storage devices are located at different locations withinthe mobile environment, a distributed storage device of the plurality ofdistributed storage devices comprising: a housing; a rotating diskstorage device within the housing; a network interface to supportcommunication with the network gateway device; a sensor to produce asensor signal indicating a characteristic of an environment external tothe housing; and a control circuit to detect an adverse operatingcondition for the rotating disk storage device based on the sensorsignal, and to transition the distributed storage device from an activestate to a standby state upon detection of the adverse operatingcondition, wherein: in the active state, the distributed storage deviceenables access of the rotating disk storage device to store a subset ofthe messages received via the network interface, to retrieve the storedsubset of the messages in response to requests received via the networkinterface, and to provide a given stored message of the stored subset ofthe messages for redundancy of storage within other distributed storagedevices of the plurality of distributed storage devices based on afrequency of requests for the given stored message; and in the standbystate, the distributed storage device prevents access to the rotatingdisk storage device, the control circuit further to determine that thedistributed storage device is operating as a leader device for theplurality of distributed storage devices, wherein the plurality ofdistributed storage devices comprises a first set of distributed storagedevices having a first reliability characteristic and a second set ofdistributed storage devices having a second, lower reliabilitycharacteristic, the control circuit further to, while the distributedstorage device is operating as the leader device: determine that thefrequency of requests for the given stored message exceeds a threshold;and forward the given stored message for storing in a distributedstorage device of the first set of distributed storage devices.
 25. Amethod comprising: providing, in a mobile environment a plurality ofdistributed storage devices coupled to a network gateway device, whereinthe network gateway device communicates messages for a plurality of userdevices within the mobile environment via a shared wireless link, andwherein at least two of the distributed storage devices of the pluralityof distributed storage devices are located at different locations withinthe mobile environment; operating a distributed storage device in anactive state, the operating comprising: providing access of a rotatingdisk storage device to store a subset of the messages received via anetwork interface; retrieving the stored subset of the messages inresponse to requests received via the network interface; and providing agiven stored message of the stored subset of the messages for redundancyof storage within other distributed storage devices of the plurality ofdistributed storage devices based on a frequency of requests for thegiven stored message; detecting an adverse operating condition for therotating disk storage device of the distributed storage device based ona sensor signal from a sensor of the distributed storage deviceindicating a characteristic of an environment of the distributed storagedevice; transitioning the distributed storage device from the activestate to a standby state upon detection of the adverse operatingcondition; preventing, in the standby state, access to the rotating diskstorage device; and determining that the distributed storage device isoperating as a leader device for the plurality of distributed storagedevices, and, while the distributed storage device is operating as theleader device: determining a message redundancy for the given storedmessage based on comparing the frequency of requests for the givenstored message to a threshold; and forwarding the given stored messagefor storing in one or more distributed storage devices of the pluralityof distributed storage devices based on the message redundancy.
 26. Themethod of claim 25, further comprising: transmitting, upon transitioningfrom the active state to the standby state, an indication that thedistributed storage device is unavailable.
 27. The method of claim 25,further comprising: configuring, in the standby state, the rotating diskstorage device in a protected state.
 28. The method of claim 25, furthercomprising: detecting, in the standby state, a safe operating conditionfor the rotating disk storage device based on the sensor signal; andtransitioning the distributed storage device from the standby state tothe active state upon detection of the safe operating condition.
 29. Themethod of claim 25, further comprising: determining a change for anindex of stored messages across the plurality of distributed storagedevices; and broadcasting the change for the index to the plurality ofdistributed storage devices.
 30. The method of claim 29, furthercomprising: determining that the distributed storage device is no longeroperating as the leader device for the plurality of distributed storagedevices; monitoring broadcast messages for indications of changes to theindex; and updating the index upon based on received indications ofchanges to the index.
 31. The method of claim 29, further comprising:monitoring for periodic status messages from the plurality ofdistributed storage devices; determining that a second distributedstorage device from the plurality of distributed storage devices isunavailable based upon not receiving a periodic status message from thesecond distributed storage device; and flagging one or more messagesstored in the second distributed storage device as unavailable in theindex.
 32. The method of claim 25, further comprising: receiving arequest for a first message; determining that the first message isstored in a first distributed storage device; retrieving the firstmessage from the first distributed storage device; and provide the firstmessage in response to the request.
 33. The method of claim 25, furthercomprising: receiving a request for a first message; determining thatthe first message is stored in a first distributed storage device; andproviding an address of the first message at the first distributedstorage device in response to the request.
 34. The method of claim 25,wherein the determining that the distributed storage device is operatingas the leader device for the plurality of distributed storage devices isbased on a result of a consensus election.
 35. The method of claim 25,further comprising: receiving information related to an impendingadverse operating condition for the rotating disk storage device; andtransitioning the distributed storage device from the active state tothe standby state based on the impending adverse operating condition.36. The method of claim 25, further comprising: detecting a failure ofthe rotating disk storage device; and broadcasting an indication thatthe distributed storage device is unavailable based on the detectedfailure.
 37. The method of claim 25, further comprising: performing aperiodic diagnostic scan on the rotating disk storage device.
 38. Themethod of claim 37, further comprising: determining one or more storagelocations of the rotating disk storage device failing the periodicdiagnostic scan; identifying one or more messages stored in the one ormore storage locations; broadcasting an indication that the one or moremessages are unavailable; and flagging the one or more storage locationsas unavailable for further use.